19 definitions across stablecoins, settlement, investing, agentic payments, compliance and security. Written to explain the mechanism rather than to sell anything — where a term has a genuine trade-off or a common misunderstanding, that is the part we spend the words on.
EURCEuro Coin
EURC is a euro-denominated stablecoin issued by Circle, holding a 1:1 target against the euro with reserves held in euro-denominated assets. It is the euro counterpart to USDC and uses the same issuance and redemption model.
Stablecoin
A stablecoin is a cryptocurrency designed to hold a constant value against a reference asset, almost always a national currency. Unlike bitcoin, whose price floats, a stablecoin targets one unit of its reference — one USDC is intended to be worth one US dollar at all times.
USDCUSD Coin
USDC is a fiat-backed stablecoin issued by Circle, designed to hold a 1:1 value against the US dollar. Reserves are held in cash and short-dated US Treasuries with regulated custodians, and Circle publishes regular attestations of those holdings.
CCTPCross-Chain Transfer Protocol
CCTP is Circle's protocol for moving USDC between blockchains by burning it on the source chain and minting it on the destination. Because no wrapped token or bridge custody is involved, the USDC that arrives is natively issued rather than a claim on a locked balance.
ERC-4337Account abstraction
ERC-4337 is an Ethereum standard that lets a smart contract act as a user's account without changing the protocol itself. It enables features an ordinary key-pair account cannot have: spending policies, session limits, social recovery, and transaction fees paid by a third party.
Settlement finality
Settlement finality is the point at which a payment becomes irreversible. Before finality a transfer can be reversed or reordered; after it, the recipient holds the value unconditionally. Different systems reach finality on very different timescales.
Cost basis
Cost basis is the original value of an asset for tax purposes — normally what was paid, adjusted for events such as splits, returns of capital and reinvested dividends. Gain or loss on disposal is the proceeds minus the basis.
DRIPDividend reinvestment plan
A dividend reinvestment plan automatically uses cash dividends to buy more of the same security instead of paying cash. Each reinvestment creates a new tax lot at the price on that date.
Form 13F
Form 13F is a quarterly SEC filing required of institutional investment managers exercising discretion over at least $100 million in qualifying US-listed securities. It discloses long positions as of quarter end and is filed within 45 days after.
Fractional shares
A fractional share is a portion of a single share of stock. Fractional investing lets someone place an order in currency terms — a fixed dollar amount — rather than in whole shares, which makes high-priced securities accessible at any budget.
MCPModel Context Protocol
The Model Context Protocol is an open standard for connecting AI models to external tools and data over JSON-RPC. An MCP server exposes capabilities — queries, actions, resources — that a model can invoke through a uniform interface rather than a bespoke integration per application.
x402
x402 is a payment protocol built on HTTP status code 402 ("Payment Required"). A server responds 402 with machine-readable payment requirements; the client pays and retries the request with a payment header; the server verifies and releases the resource. It is designed for per-request payments by software rather than people.
GENIUS Act
The GENIUS Act is US federal legislation establishing a regulatory framework for payment stablecoins, covering who may issue them, what reserves must back them, and how holders may redeem them.
MiCAMarkets in Crypto-Assets Regulation
MiCA is the European Union's regulatory framework for crypto-assets, establishing authorisation, reserve, disclosure and conduct requirements for issuers and service providers. It creates a single EU-wide regime in place of divergent national rules.
Travel Rule
The Travel Rule requires financial institutions — and, under FATF guidance, virtual asset service providers — to transmit originator and beneficiary information alongside transfers above a threshold, so that identifying data accompanies the value.
Agentic payment security
Agentic payment security covers the failure modes specific to payments initiated by autonomous software rather than people. The distinctive risks are substitution between resources, duplicate settlement under concurrency, spending beyond an authorised allowance, and pricing that the payer cannot verify before paying.
MPCMulti-party computation
Multi-party computation lets several parties jointly compute a result without any of them learning the others' inputs. Applied to wallets, it splits a private key into shares held separately, so a transaction can be signed without the whole key ever existing in one place.
Passkey
A passkey is a WebAuthn credential stored on a user's device or in their platform keychain, unlocked by biometrics or a device PIN. It replaces a password with a key pair: the site stores a public key, and the private key never leaves the device.
WebAuthnWeb Authentication
WebAuthn is a web standard for authenticating with public-key cryptography instead of shared secrets. The private key never leaves the user's device, and signatures are bound to the requesting site's origin, which makes credentials useless to a phishing site even if the user is fully deceived.